Author: Robert Hyatt
Date: 14:47:48 05/28/02
Go up one level in this thread
On May 28, 2002 at 16:34:12, Vincent Diepeveen wrote: >On May 28, 2002 at 15:42:33, Robert Hyatt wrote: > >>On May 28, 2002 at 14:36:36, Vincent Diepeveen wrote: >> >>>On May 28, 2002 at 12:53:44, Robert Hyatt wrote: >>> >>>>On May 28, 2002 at 10:06:42, Vincent Diepeveen wrote: >>>> >>>>>On May 28, 2002 at 09:06:36, K. Burcham wrote: >>>>> >>>>>for computerchess that is way too optimistic Kim. >>>>> >>>>>programs like Cray Blitz or DIEP might do pretty well at >>>>>8 processors, but crafty, fritz, sos, shredder, patzer, >>>>>junior and these programs >>>>>scale pretty bad at 8 processors. >>>> >>>> >>>>What on earth are you talking about when you mention Crafty? I have >>>>run crafty on 16 cpu machines and it works just as well as it does on >>>>4... From actual testing, not "speculation". >>> >>>i'm talking about worst case speedup. >>> >>>*not* average case or best case. We both know that some>>testset positions you could get 100 times speedup with some luck >>>on a 16 processor. >>> >> >>happens _very_ rarely. In fact, in my test set that I use I _never_ >>get a speedup beyond 4.0 on my quad. I weed the oddball positions out. >>I also am not aware of any positions where I get a "speedup < 2.0" on a >>quad either. Perhaps one exists. But one outlying data point is not >>very interesting. It is the "usual" performance that I try to worry >>about. > >instead of that testset you should use a bunch of positions >from crafty in world championships. like against junior. >I still do not understand how it managed to blow this. That is where most of my "test positions" come from. Key game positions I have seen over the years. Sometimes several positions from successive moves in the game in fact. > >pawn up! > >most likely score went down there. though it was only 2 processors, >same lemma applies. fail lows don't particularly affect parallel efficiency in Crafty, neither does fail highs. Most searches have fail lows and fail highs distributed throughout them anyway... handling a "fail low" is a different issue from searching the resulting tree. It is pretty easy to mis-handle one whether you have a parallel search or not.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.